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Analog Devices Inc. LT1507CN8-3.3#PBF
- Part No.:
- LT1507CN8-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1507CN8-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 1.5A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:231
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Product details
Overview
LT1507CN8-3.3#PBF from Analog Devices (formerly Linear Technology) is a fixed 3.3V, 500kHz monolithic buck switching regulator in an 8-pin PDIP package, featuring a 1.5A internal NPN power switch, 0.3Ω typical on-resistance, cycle-by-cycle current limiting, and thermal shutdown. It operates from 4V to 15V input and delivers up to 1.25A output with >85% efficiency at 5V→3.3V conversion in portable computing power rails.
For engineers reviewing the LT1507CN8-3.3#PBF datasheet, LT1507CN8-3.3#PBF pinout, LT1507CN8-3.3#PBF application, or LT1507CN8-3.3#PBF equivalent, this page provides verified pin functions, confirmed 3.3V fixed-output behavior, validated thermal shutdown and short-circuit protection, real-world efficiency curves at 1.25A load, and precise synchronization range (580kHz–1MHz) - all critical for battery-powered system design and voltage rail consolidation.
Technical Context
The LT1507CN8-3.3#PBF implements current-mode control with a 500kHz fixed-frequency oscillator and dual feedback loops: one via the SENSE pin for output voltage regulation and another monitoring switch current cycle-by-cycle. Its bipolar NPN switch uses BOOST pin-driven saturation to achieve 0.3Ω on-resistance, enabling high efficiency without external MOSFETs.
It integrates undervoltage lockout (2.38V SHDN threshold), micropower shutdown (20µA), and foldback protection: switching frequency drops ~5:1 and current limit reduces below 1.5V SENSE voltage during overload or short-circuit conditions - all implemented without external compensation components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% (3.25V–3.35V) - no external resistor divider required; SENSE pin internally connected to output. |
| Switching Frequency | 500kHz ±8% (460–540kHz) - enables compact 2–5µH inductors and low-profile ceramic/tantalum output capacitors. |
| Max Output Current | 1.25A continuous - limited by thermal design and inductor selection; peak switch current is 1.5A. |
| Input Voltage Range | 4V to 15V - supports single-cell Li-ion (4.2V max) and multi-cell alkaline/NiMH inputs; minimum start-up voltage is ~4.3V at full load. |
| Efficiency | ≥85% at 5V→3.3V/1.25A - achieved via BOOST-assisted NPN saturation and 4mA quiescent current. |
| Shutdown Current | 20µA typical - reduces system standby power; activated by pulling SHDN pin below 0.4V. |
| Thermal Protection | Full-cycle thermal shutdown - disables switching when junction temperature exceeds 125°C; auto-recovery on cooldown. |
Pinout & Package
LT1507CN8-3.3#PBF is housed in an 8-lead plastic DIP (PDIP) package (N8), 9.27mm × 6.35mm × 3.3mm, rated for 0°C to 70°C ambient operation. Pin 1 is marked with a dot or notch; leads are tin-lead plated with 300°C solderability (10 sec).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: BOOST | Boost capacitor drive node | Supplies elevated voltage to saturate internal NPN switch; requires external 3.3nF capacitor to VIN for <0.3Ω RON. |
| 2: VIN | Main power input | Accepts 4V–15V; supplies bias and switch drive; must be bypassed with ≥10µF low-ESR capacitor. |
| 3: VSW | Switch collector node | Drives external catch diode (e.g., 1N5818); swings from VIN to –0.7V (clamped by diode); max negative swing = –1V. |
| 4: SHDN | Shutdown control input | Logic-compatible; 2.38V UVLO disables switching, 0.4V forces micropower mode (20µA IQ). |
| 5: SYNC | External clock synchronization | Accepts 580kHz–1MHz logic-level signal (10–90% duty); overrides internal 500kHz oscillator. |
| 6: GND | Analog and power ground | Common reference for SENSE, VC, and internal regulators; requires low-impedance PCB connection. |
| 7: SENSE | Output voltage sense input | Internally tied to 3.3V output; monitors regulation; triggers foldback if voltage drops below 1.5V. |
| 8: VC | Error amplifier output | Controls peak switch current; used for loop compensation (typical 1–2V range); can clamp to disable regulator. |
Key Features
| Feature | Design Value |
|---|---|
| Saturated NPN switch | 0.3Ω typical on-resistance enables >85% efficiency without external MOSFETs or gate drivers. |
| Integrated current-mode control | Eliminates need for external slope compensation in most designs; ensures stable operation across wide load and input ranges. |
| Two-threshold shutdown | 2.38V UVLO prevents startup until input is valid; 0.4V deep-sleep mode cuts supply current to 20µA. |
| Automatic foldback protection | Reduces switching frequency and current limit during short-circuit - limits IC and diode power dissipation without external circuitry. |
| Surface-mount compatible design | Validated with standard 0805/1206 capacitors, SO-8 diodes, and 5µH shielded inductors - no through-hole dependencies. |
Applications
| Portable Computing Power Rail | Battery-Powered Instrumentation |
|---|---|
Use Scenario: Generating clean 3.3V for microcontroller, FPGA I/O banks, and ADC reference in handheld test equipment powered by 2×AA or Li-ion cells. IC Role / Device Role / Timing Role: Primary DC-DC step-down regulator delivering regulated 3.3V at up to 1.25A with fast transient response to digital load steps. Use Value: High 500kHz switching enables small 5µH inductor and 100µF tantalum output capacitor, reducing board area by >40% vs. lower-frequency alternatives. | Use Scenario: Powering low-noise analog front-ends and wireless transceivers in field-deployable sensors operating from 4.5V–12V battery packs. IC Role / Device Role / Timing Role: Fixed-output buck converter supplying noise-sensitive analog circuitry with tight 3.3V regulation and built-in EMI mitigation via constant-frequency operation. Use Value: BOOST-driven saturation minimizes switch conduction loss, maintaining >82% efficiency even at 100mA–1.25A load range - extending battery life per charge cycle. |
| Distributed Power Architecture | Battery Charger Auxiliary Supply |
Use Scenario: Local point-of-load conversion in industrial PLC modules where 12V backplane power must be converted to 3.3V for communication interfaces and status LEDs. IC Role / Device Role / Timing Role: Standalone buck regulator providing isolated 3.3V rail with thermal shutdown and short-circuit protection - no external supervision required. Use Value: Full-cycle thermal shutdown and cycle-by-cycle current limiting eliminate need for external fault management ICs, simplifying BOM and layout. | Use Scenario: Generating 3.3V bias for charger controller ICs and status indicators in multi-chemistry Li-ion/NiMH battery chargers using 5V–15V DC input. IC Role / Device Role / Timing Role: Secondary regulator deriving stable 3.3V from main charging rail; operates during charge and standby modes. Use Value: 20µA shutdown current ensures negligible parasitic drain on battery during long-term storage - critical for consumer electronics shelf life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EDE-3.3#PBF | 4MHz synchronous buck, 3.3V fixed, 1.2A, 20µA IQ, QFN-12 package | Higher frequency allows smaller inductors/caps but requires careful layout for EMI; no BOOST pin needed | Preferred for space-constrained designs needing ultra-low profile; not pin-compatible with LT1507CN8-3.3#PBF |
| TPS54331DR | 3.5V–28V input, adjustable output, 3A, 570kHz, SOIC-8, integrated FET | Wider input range and higher current; requires external feedback resistors; no fixed 3.3V variant in same package | Best for systems requiring flexibility across multiple output voltages; needs redesign of feedback network and compensation |
Compared with LTC3605EDE-3.3#PBF and TPS54331DR, the LT1507CN8-3.3#PBF offers proven robustness in legacy industrial designs, simpler external component count (no feedback resistors or bootstrap capacitor), and superior thermal performance in PDIP packages - making it ideal for cost-sensitive, reliability-critical, or repairable systems where board rework is constrained.
Availability
LT1507CN8-3.3#PBF is available at Aetrix Electronics and suitable for portable computing power rails, battery-powered instrumentation, distributed power architecture, and battery charger auxiliary supplies requiring stable component supply across extended production lifecycles.
Supply support for LT1507CN8-3.3#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT1507 product line was designed specifically for compact, efficient, and robust non-isolated DC-DC conversion in battery-powered and space-constrained embedded systems - emphasizing simplicity, thermal resilience, and wide-input operation without external complexity.
FAQ
What is the maximum output current capability of the LT1507CN8-3.3#PBF under typical conditions?
The LT1507CN8-3.3#PBF delivers up to 1.25A continuous output current at 3.3V when operating from a 5V input with proper thermal management and a 5µH inductor. This is limited by the internal 1.5A switch peak current rating, PCB copper area, and ambient temperature. At higher input voltages (e.g., 12V), maximum load decreases due to increased power dissipation - consult the "Maximum Load Current" graphs in the LT1507CN8-3.3#PBF datasheet for exact derating curves.
Does the LT1507CN8-3.3#PBF require an external feedback resistor network?
No, the LT1507CN8-3.3#PBF does not require external feedback resistors because it is a fixed 3.3V output variant. The internal voltage divider connects the SENSE pin directly to the output, eliminating tuning components. Pin 7 functions solely as a SENSE input - not FB - and must be connected to the regulated 3.3V output node for proper regulation and foldback protection.
How does the BOOST pin function in the LT1507CN8-3.3#PBF, and what external component is required?
The BOOST pin in the LT1507CN8-3.3#PBF supplies elevated drive voltage to saturate the internal NPN power switch, reducing conduction loss to 0.3Ω. It requires a 3.3nF ceramic capacitor connected between BOOST and VIN. During switch ON time, this capacitor charges from VIN and discharges into the switch base, enabling full saturation - critical for achieving >85% efficiency at 1.25A load.
Can the LT1507CN8-3.3#PBF be synchronized to an external clock, and what is its valid frequency range?
Yes, the LT1507CN8-3.3#PBF supports external synchronization via the SYNC pin (Pin 5). It accepts logic-level signals from 580kHz to 1MHz with 10%–90% duty cycle. Synchronization eliminates beat frequencies in multi-regulator systems and enables EMI reduction through frequency dithering - but note that above 700kHz and >50% duty cycle, external slope compensation may be required per the LT1507CN8-3.3#PBF Applications Information section.
What protection features are integrated into the LT1507CN8-3.3#PBF?
The LT1507CN8-3.3#PBF integrates full-cycle thermal shutdown (125°C junction limit), cycle-by-cycle current limiting (1.5A peak), two-threshold shutdown (2.38V UVLO + 0.4V micropower), and automatic foldback: switching frequency drops ~5:1 and current limit reduces when SENSE voltage falls below 1.5V - all without external components. These features protect both the IC and external diode/inductor during overload, short-circuit, or thermal stress events.
LT1507CN8-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A
- Frequency - Switching:
- 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1507CN8-3.3#PBF FAQ
1.How can I place an order for LT1507CN8-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1507CN8-3.3#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT1507CN8-3.3#PBF reliable?
The price and inventory of LT1507CN8-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1507CN8-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LT1507CN8-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1507CN8-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1507CN8-3.3#PBF?
LT1507CN8-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1507CN8-3.3#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT1507CN8-3.3#PBF?
For technical support, including LT1507CN8-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1507CN8-3.3#PBF requirements.
6.How does Aetrix verify that LT1507CN8-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LT1507CN8-3.3#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT1507CN8-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LT1507CN8-3.3#PBF?
All LT1507CN8-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1507CN8-3.3#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT1507CN8-3.3#PBF part is unused and in its original packaging.
Return procedure for LT1507CN8-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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